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All sourcesNASA NTRSDOE OSTI
NASA NTRS1999

Endocrine relationships during human spaceflight

Human spaceflight is associated with a chronic loss of protein from muscle. The objective of this study was to determine whether changes in urinary hormone excretion could identify a hormonal role for this loss. Urine samples were collected from the crews of two Life Sciences Space Shuttle missions before and during spaceflight. Data are means +/- SE with the number of subjects in parentheses. The first value is the mean preflight measurement, and the second value is the mean inflight measurement. Adrenocorticotropic hormone (ACTH) [27.7 +/- 4.4 (9) vs. 25.1 +/- 3.4 (9) ng/day], growth hormone [724 +/- 251 (9) vs. 710 +/- 206 (9) ng/day], insulin-like growth factor I [6.81 +/- 0.62 vs. 6.04 +/- 0.51 (8) nM/day], and C-peptide [44.9 +/- 8.3 (9) vs. 50.7 +/- 10.3 (9) micrograms/day] were unchanged with spaceflight. In contrast, free 3,5,3'-triiodothyronine [791 +/- 159 (9) vs. 371 +/- 41 (9) pg/day, P < 0.05], prostaglandin E2 (PGE2) [1, 064 +/- 391 (8) vs. 465 +/- 146 (8) ng/day, P < 0.05], and its metabolite PGE-M [1,015 +/- 98 (9) vs. 678 +/- 105 (9) ng/day, P < 0. 05] were decreased inflight. The urinary excretion of most hormones returned to their preflight levels during the postflight period, with the exception of ACTH [47.5 +/- 10.3 (9) ng/day], PGE2 [1,433 +/- 327 (8) ng/day], PGF2alpha, [2,786 +/- 313 (8) ng/day], and its metabolite PGF-M [4,814 +/- 402 (9) ng/day], which were all increased compared with the preflight measurement (P < 0.05). There was a trend for urinary cortisol to be elevated inflight [55.3 +/- 5. 9 (9) vs. 72.5 +/- 11.1 micrograms/day, P = 0.27] and postflight [82.7 +/- 8.6 (8) micrograms/day, P = 0.13]. The inflight human data support ground-based in vitro work showing that prostaglandins have a major role in modulating the changes in muscle protein content in response to tension or the lack thereof.

Flight Experiment↗
NASA NTRS1997

Cardiovascular consequences of bed rest: effect on maximal oxygen uptake

Maximal oxygen uptake (VO2max) is reduced in healthy individuals confined to bed rest, suggesting it is independent of any disease state. The magnitude of reduction in VO2max is dependent on duration of bed rest and the initial level of aerobic fitness (VO2max), but it appears to be independent of age or gender. Bed rest induces an elevated maximal heart rate which, in turn, is associated with decreased cardiac vagal tone, increased sympathetic catecholamine secretion, and greater cardiac beta-receptor sensitivity. Despite the elevation in heart rate, VO2max is reduced primarily from decreased maximal stroke volume and cardiac output. An elevated ejection fraction during exercise following bed rest suggests that the lower stroke volume is not caused by ventricular dysfunction but is primarily the result of decreased venous return associated with lower circulating blood volume, reduced central venous pressure, and higher venous compliance in the lower extremities. VO2max, stroke volume, and cardiac output are further compromised by exercise in the upright posture. The contribution of hypovolemia to reduced cardiac output during exercise following bed rest is supported by the close relationship between the relative magnitude (% delta) and time course of change in blood volume and VO2max during bed rest, and also by the fact that retention of plasma volume is associated with maintenance of VO2max after bed rest. Arteriovenous oxygen difference during maximal exercise is not altered by bed rest, suggesting that peripheral mechanisms may not contribute significantly to the decreased VO2max. However reduction in baseline and maximal muscle blood flow, red blood cell volume, and capillarization in working muscles represent peripheral mechanisms that may contribute to limited oxygen delivery and, subsequently, lowered VO2max. Thus, alterations in cardiac and vascular functions induced by prolonged confinement to bed rest contribute to diminution of maximal oxygen uptake and reserve capacity to perform physical work.

Non-NASA Center↗
NASA NTRS1997

Baroreflex regulation of blood pressure during dynamic exercise

From the work of Potts et al. Papelier et al. and Shi et al. it is readily apparent that the arterial (aortic and carotid) baroreflexes are reset to function at the prevailing ABP of exercise. The blood pressure of exercise is the result of the hemodynamic (cardiac output and TPR) responses, which appear to be regulated by two redundant neural control systems, "Central Command" and the "exercise pressor reflex". Central Command is a feed-forward neural control system that operates in parallel with the neural regulation of the locomotor system and appears to establish the hemodynamic response to exercise. Within the central nervous system it appears that the HLR may be the operational site for Central Command. Specific neural sites within the HLR have been demonstrated in animals to be active during exercise. With the advent of positron emission tomography (PET) and single-photon emission computed tomography (SPECT), the anatomical areas of the human brain related to Central Command are being mapped. It also appears that the Nucleus Tractus Solitarius and the ventrolateral medulla may serve as an integrating site as they receive neural information from the working muscles via the group III/IV muscle afferents as well as from higher brain centers. This anatomical site within the CNS is now the focus of many investigations in which arterial baroreflex function, Central Command and the "exercise pressor reflex" appear to demonstrate inhibitory or facilitatory interaction. The concept of whether Central Command is the prime mover in the resetting of the arterial baroreceptors to function at the exercising ABP or whether the resetting is an integration of the "exercise pressor reflex" information with that of Central Command is now under intense investigation. However, it would be justified to conclude, from the data of Bevegard and Shepherd, Dicarlo and Bishop, Potts et al., and Papelier et al. that the act of exercise results in the resetting of the arterial baroreflex. In addition, if, as we have proposed, the cardiopulmonary baroreceptors primarily monitors and reflexly regulates cardiac filling volume, it would seem from the data of Mack et al. and Potts et al. that the cardiopulmonary baroreceptor is also reset at the beginning of exercise. Therefore, investigations of the neural mechanisms of regulation involving Central Command and cardiopulmonary afferents, similar to those being undertaken for the arterial baroreflex, need to be established.

NASA Discipline Cardiopulmonary↗
NASA NTRS1996

[Heart functions in monkeys during a 2-week antiorthostatic hypokinesia]

Dynamics of the left heart ventricular muscle contractility and compliance was studied in 4 monkeys in the head down position (antiorthostatic hypokinesia) with the body angle 10 during 2 weeks. Functional tests on a tilt table and under two conditions of centrifuge rotation were performed prior to and after the antiorthostatic hypokinesia. No changes in the left heart ventricular muscle contractility was found. However, the sensitivity level of the baroreflex control decreased. Compliance of the left heart myocardial fibre increased in the first hours and days of the antiorthostatic hypokinesia.

NASA Discipline Regulatory Physiology↗
NASA NTRS1999

Regulatory Physiology

As noted elsewhere in this report, a central goal of the Extended Duration Orbiter Medical Project (EDOMP) was to ensure that cardiovascular and muscle function were adequate to perform an emergency egress after 16 days of spaceflight. The goals of the Regulatory Physiology component of the EDOMP were to identify and subsequently ameliorate those biochemical and nutritional factors that deplete physiological reserves or increase risk for disease, and to facilitate the development of effective muscle, exercise, and cardiovascular countermeasures. The component investigations designed to meet these goals focused on biochemical and physiological aspects of nutrition and metabolism, the risk of renal (kidney) stone formation, gastrointestinal function, and sleep in space. Investigations involved both ground-based protocols to validate proposed methods and flight studies to test those methods. Two hardware tests were also completed.

Lane, Helen W.↗
NASA NTRS1994

Space shuttle flight (STS-45) of L8 myoblast cells results in the isolation of a nonfusing cell line variant

Myoblast cell cultures have been widely employed in conventional (1g) studies of biological processes because characteristics of intact muscle can be readily observed in these cultured cells. We decided to investigate the effects of spaceflight on muscle by utilizing a well characterized myoblast cell line (L8 rat myoblasts) as cultured in the recently designed Space Tissue Loss Flight Module "A" (STL-A). The STL-A is a "state of the art," compact, fully contained, automated cell culture apparatus which replaces a single mid-deck locker on the Space Shuttle. The L8 cells were successfully flown in the STL-A on the Space Shuttle STS-45 mission. Upon return to earth, reculturing of these spaceflown L8 cells (L8SF) resulted in their unexpected failure to fuse and differentiate into myotubes. This inability of the L8SF cells to fuse was found to be a permanent phenotypic alteration. Scanning electron microscopic examination of L8SF cells growing at 1g on fibronectin-coated polypropylene fibers exhibited a strikingly different morphology as compared to control cells. In addition to their failure to fuse into myotubes, L8SF cells also piled up on top of each other. When assayed in fusion-promoting soft agar, L8SF cells gave rise to substantially more and larger colonies than did either preflight (L8AT) or ground control (L8GC) cells. All data to this point indicate that flying L8 rat myoblasts on the Space Shuttle for a duration of 7-10 d at subconfluent densities results in several permanent phenotypic alterations in these cells.

STS-45 Shuttle Project↗
NASA NTRS1992

Oxygen transport and cardiovascular function at extreme altitude: lessons from Operation Everest II

Operation Everest II was designed to examine the physiological responses to gradual decompression simulating an ascent of Mt Everest (8,848 m) to an inspired PO2 of 43 mmHg. The principal studies conducted were cardiovascular, respiratory, muscular-skeletal and metabolic responses to exercise. Eight healthy males aged 21-31 years began the "ascent" and six successfully reached the "summit", where their resting arterial blood gases were PO2 = 30 mmHg and PCO2 = 11 mmHg, pH = 7.56. Their maximal oxygen uptake decreased from 3.98 +/- 0.2 L/min at sea level to 1.17 +/- 0.08 L/min at PIO2 43 mmHg. The principal factors responsible for oxygen transport from the atmosphere to tissues were (1) Alveolar ventilation--a four fold increase. (2) Diffusion from the alveolus to end capillary blood--unchanged. (3) Cardiac function (assessed by hemodynamics, echocardiography and electrocardiography)--normal--although maximum cardiac output and heart rate were reduced. (4) Oxygen extraction--maximal with PvO2 14.8 +/- 1 mmHg. With increasing altitude maximal blood and muscle lactate progressively declined although at any submaximal intensity blood and muscle lactate was higher at higher altitudes.

Non-NASA Center↗
NASA NTRS1992

Pulmonary and leg VO2 during submaximal exercise: implications for muscular efficiency

Insights into muscle energetics during exercise (e.g., muscular efficiency) are often inferred from measurements of pulmonary gas exchange. This procedure presupposes that changes of pulmonary O2 (VO2) associated with increases of external work reflect accurately the increased muscle VO2. The present investigation addressed this issue directly by making simultaneous determinations of pulmonary and leg VO2 over a range of work rates calculated to elicit 20-90% of maximum VO2 on the basis of prior incremental (25 or 30 W/min) cycle ergometry. VO2 for both legs was calculated as the product of twice one-leg blood flow (constant-infusion thermodilution) and arteriovenous O2 content difference across the leg. Measurements were made 3-5 min after each work rate imposition to avoid incorporation of the VO2 slow component above the lactate threshold. For all 17 subjects, the slope of pulmonary VO2 (9.9 +/- 0.2 ml O2.W-1.min-1) was not different (P greater than 0.05) from that for leg VO2 (9.2 +/- 0.6 ml O2.W-1.min-1). Estimation of "delta" efficiency (i.e., delta work accomplished divided by delta energy expended, calculated from slope of VO2 vs. work rate and a caloric equivalent for O2 of 4.985 cal/ml) using pulmonary VO2 measurements (29.1 +/- 0.6%) was likewise not significantly different (P greater than 0.05) from that made using leg VO2 measurements (33.7 +/- 2.4%). These data suggest that the net VO2 cost of metabolic "support" processes outside the exercising legs changes little over a relatively broad range of exercise intensities. Thus, under the conditions of this investigation, changes of VO2 measured from expired gas reflected closely those occurring within the exercising legs.

Non-NASA Center↗
NASA NTRS1991

Palmitate stimulates glucose transport in rat adipocytes by a mechanism involving translocation of the insulin sensitive glucose transporter (GLUT4)

In rat adipocytes, palmitate: a) increases basal 2-deoxyglucose transport 129 +/- 27% (p less than 0.02), b) decreases the insulin sensitive glucose transporter (GLUT4) in low density microsomes and increases GLUT4 in plasma membranes and c) increases the activity of the insulin receptor tyrosine kinase. Palmitate-stimulated glucose transport is not additive with the effect of insulin and is not inhibited by the protein kinase C inhibitors staurosporine and sphingosine. In rat muscle, palmitate: a) does not affect basal glucose transport in either the soleus or epitrochlearis and b) inhibits insulin-stimulated glucose transport by 28% (p less than 0.005) in soleus but not in epitrochlearis muscle. These studies demonstrate a potentially important differential role for fatty acids in the regulation of glucose transport in different insulin target tissues.

NASA Discipline Cell Biology↗
NASA NTRS2005

Using EMG to anticipate head motion for virtual-environment applications

In virtual environment (VE) applications, where virtual objects are presented in a see-through head-mounted display, virtual images must be continuously stabilized in space in response to user's head motion. Time delays in head-motion compensation cause virtual objects to "swim" around instead of being stable in space which results in misalignment errors when overlaying virtual and real objects. Visual update delays are a critical technical obstacle for implementing head-mounted displays in applications such as battlefield simulation/training, telerobotics, and telemedicine. Head motion is currently measurable by a head-mounted 6-degrees-of-freedom inertial measurement unit. However, even given this information, overall VE-system latencies cannot be reduced under about 25 ms. We present a novel approach to eliminating latencies, which is premised on the fact that myoelectric signals from a muscle precede its exertion of force, thereby limb or head acceleration. We thus suggest utilizing neck-muscles' myoelectric signals to anticipate head motion. We trained a neural network to map such signals onto equivalent time-advanced inertial outputs. The resulting network can achieve time advances of up to 70 ms.

Clinical Trial↗
NASA NTRS2004

Kinematid Parameters of Corrective Postural Responses Differ between Upper and Lower Body Perturbations

Balance control is disrupted following prolonged microgravity exposure, and to better understand this, both upper and lower body perturbations have been used to study postural control in space flight crewmembers. However, differences between several postural response indicators observed using the two techniques suggest that different sensory systems may be involved in organizing responses to these different perturbation approaches. The present study sought to compare differences in parameters of corrective postural responses between upper body perturbations (pushes to the chest) and forward translations of the support surface. Nine subjects participated in this study. Forward translations were performed using a NeuroCom EquiTest(TM) CDP system, which was synchronized with a Northern Digital OptoTrak motion tracking system (3 subjects). Chest pushes were applied using a hand-held force transducer device and were performed using a stabilometric system (6 subjects). Analysis of EMG has shown that: i) the earliest response of the leg muscles was registered significantly later during forward translation of the support surface than during chest pushes, and ii) there was a tendency for the different order of leg muscles activation during the translation tests. Analysis of the kinematic data showed a significant difference in the subject's body segments inclinations during corrective postural responses to upper and lower body perturbations. It appears that upper body perturbations likely engage the vestibular system more rapidly, while lower body perturbations likely engage somatosensory systems more rapidly. These differences must be taken into account when choosing the type of perturbation for testing postural function.

Sayenko, G.↗
NASA NTRS2006

Comparison of Interstitial Fluid pH, PCO2, PO2 with Venous Blood Values During Repetitive Handgrip Exercise

We evaluated the use of a small, fiber optic sensor to measure pH, PCO2 and PO2 from forearm muscle interstitial fluid (IF) during handgrip dynamometry. PURPOSE: Compare pH, PCO2 and PO2 values obtained from venous blood with those from the IF of the flexor digitorum superficialis (FDS) during three levels of exercise intensity. METHODS: Six subjects (5M/1F), average age 29+/-5 yrs, participated in the study. A venous catheter was placed in the retrograde direction in the antecubital space and a fiber optic sensor (Paratrend, Diametrics Medical, Inc.) was placed through a 22 G catheter into the FDS muscle under ultrasound guidance. After a 45 min rest period, subjects performed three 5-min bouts of repetitive handgrip exercise (2s contraction/1 s relaxation) at attempted levels of 15%, 30% and 45% of maximal voluntary contraction. The order of the exercise bouts was random with the second and third bouts started after blood lactate had returned to baseline. Venous blood was sampled every minute during exercise and analyzed with an I-Stat CG-4+ cartridge, while IF fiber optic sensor measurements were obtained every 2 s. Change from pre-exercise baseline to end of exercise was computed for pH, PCO2 and PO2. Blood and IF values were compared with a paired t-test. RESULTS: Baseline values for pH, PCO2 and PO2 were 7.37+/-0.02, 46+/-4 mm Hg, and 36+/-6 mm Hg respectively in blood and 7.39+/-0.02, 44+/-6 mm Hg, and 35+/-14 mm Hg in IF. Average changes over all exercise levels are noted in the Table below. For each parameter the exercise-induced change was at least twice as great in IF as in blood. In blood and IF, pH and PCO2 increases were directly related to exercise intensity. Change in venous PO2 was unrelated to exercise intensity, while IF PO2 decreased with increases in exercise intensity. CONCLUSIONS: Measurement of IF pH, PCO2 and PO2 is more sensitive to exercise intensity than measurement of the same parameters in venous blood and provides continuous assessment during and after exercise.

Hagan, Ronald Donald↗
NASA NTRS2005

Brain-Computer Interfaces for 1-D and 2-D Cursor Control: Designs Using Volitional Control of the EEG Spectrum or Steady-State Visual Evoked Potentials

We have developed and tested two EEG-based brain-computer interfaces (BCI) for users to control a cursor on a computer display. Our system uses an adaptive algorithm, based on kernel partial least squares classification (KPLS), to associate patterns in multichannel EEG frequency spectra with cursor controls. Our first BCI, Target Practice, is a system for one-dimensional device control, in which participants use biofeedback to learn voluntary control of their EEG spectra. Target Practice uses a KF LS classifier to map power spectra of 30-electrode EEG signals to rightward or leftward position of a moving cursor on a computer display. Three subjects learned to control motion of a cursor on a video display in multiple blocks of 60 trials over periods of up to six weeks. The best subject s average skill in correct selection of the cursor direction grew from 58% to 88% after 13 training sessions. Target Practice also implements online control of two artifact sources: a) removal of ocular artifact by linear subtraction of wavelet-smoothed vertical and horizontal EOG signals, b) control of muscle artifact by inhibition of BCI training during periods of relatively high power in the 40-64 Hz band. The second BCI, Think Pointer, is a system for two-dimensional cursor control. Steady-state visual evoked potentials (SSVEP) are triggered by four flickering checkerboard stimuli located in narrow strips at each edge of the display. The user attends to one of the four beacons to initiate motion in the desired direction. The SSVEP signals are recorded from eight electrodes located over the occipital region. A KPLS classifier is individually calibrated to map multichannel frequency bands of the SSVEP signals to right-left or up-down motion of a cursor on a computer display. The display stops moving when the user attends to a central fixation point. As for Target Practice, Think Pointer also implements wavelet-based online removal of ocular artifact; however, in Think Pointer muscle artifact is controlled via adaptive normalization of the SSVEP. Training of the classifier requires about three minutes. We have tested our system in real-time operation in three human subjects. Across subjects and sessions, control accuracy ranged from 80% to 100% correct with lags of 1-5 seconds for movement initiation and turning.

Trejo, Leonard J.↗
NASA NTRS2004

The Art of Space Flight Exercise Hardware: Design and Implementation

The design of space flight exercise hardware depends on experience with crew health maintenance in a microgravity environment, history in development of flight-quality exercise hardware, and a foundation for certifying proper project management and design methodology. Developed over the past 40 years, the expertise in designing exercise countermeasures hardware at the Johnson Space Center stems from these three aspects of design. The medical community has steadily pursued an understanding of physiological changes in humans in a weightless environment and methods of counteracting negative effects on the cardiovascular and musculoskeletal system. The effects of weightlessness extend to the pulmonary and neurovestibular system as well with conditions ranging from motion sickness to loss of bone density. Results have shown losses in water weight and muscle mass in antigravity muscle groups. With the support of university-based research groups and partner space agencies, NASA has identified exercise to be the primary countermeasure for long-duration space flight. The history of exercise hardware began during the Apollo Era and leads directly to the present hardware on the International Space Station. Under the classifications of aerobic and resistive exercise, there is a clear line of development from the early devices to the countermeasures hardware used today. In support of all engineering projects, the engineering directorate has created a structured framework for project management. Engineers have identified standards and "best practices" to promote efficient and elegant design of space exercise hardware. The quality of space exercise hardware depends on how well hardware requirements are justified by exercise performance guidelines and crew health indicators. When considering the microgravity environment of the device, designers must consider performance of hardware separately from the combined human-in-hardware system. Astronauts are the caretakers of the hardware while it is deployed and conduct all sanitization, calibration, and maintenance for the devices. Thus, hardware designs must account for these issues with a goal of minimizing crew time on orbit required to complete these tasks. In the future, humans will venture to Mars and exercise countermeasures will play a critical role in allowing us to continue in our spirit of exploration. NASA will benefit from further experimentation on Earth, through the International Space Station, and with advanced biomechanical models to quantify how each device counteracts specific symptoms of weightlessness. With the continued support of international space agencies and the academic research community, we will usher the next frontier in human space exploration.

Beyene, Nahom M.↗
NASA NTRS2006

Changes in Nutritional Issues Over the Last 45 Years

The prospect of a lunar outpost to conduct science and learn how to live and work off the Earth is exciting. The nutritional sciences will focus on the issues of over all health, with emphasis on skeletal muscle health and prevention of radiation damage. There is a great deal of research needed to determine the nutritional and food component potential for preventing the changes that occur in space flight. Further research is also needed on the interactions of systems and countermeasures, such as protein-amino acid needs for enhancement of muscle protein synthesis while not being detrimental for bone health. The interrelationship between radiation exposure, nutrition, and food components has just begun.

Lane, Helen W.↗
NASA NTRS2006

Artificial Gravity as a Multi-System Countermeasure to Bed Rest Deconditioning: Preliminary Results

Artificial gravity paradigms may offer effective, efficient, multi-system protection from the untoward effects of adaptation to the microgravity of space or the hypogravity of planetary surfaces. Intermittent artificial gravity (AG) produced by a horizontal short-radius centrifuge (SRC) has recently been utilized on human test subjects deconditioned by bed rest. This presentation will review preliminary results of a 41 day study conducted at the University of Texas Medical Branch, Galveston, TX bed rest facility. During the first eleven days of the protocol, subjects were ambulatory, but confined to the facility. They began a carefully controlled diet, and participated in multiple baseline tests of bone, muscle, cardiovascular, sensory-motor, immunological, and psychological function. On the twelfth day, subjects entered the bed rest phase of the study, during which they were confined to strict 6deg head down tilt bed rest for 21 days. Beginning 24 hrs into this period, treatment subjects received one hour daily exposures to artificial gravity which was produced by spinning the subjects on a 3.0 m radius SRC. They were oriented radially in the supine position so that the centrifugal force was aligned with their long body axis, and while spinning, they "stood" on a force plate, supporting the centrifugal loading (2.5 g at the feet, 1.0 g at the heart). The subject station allowed free translation over approximately 10 cm to ensure full loading of the lower extremities and to allow for anti-orthostatic muscle contractions. Control subjects were positioned on the centrifuge but did not spin. Following the bed rest phase, subjects were allowed to ambulate again, but remained within the facility for an additional 9 days and participated in multiple follow-up tests of physiological function.

Warren, L. E.↗
NASA NTRS2006

An Optimization of Pulsed ElectroMagnetic Fields Study

To date, in our research we have focused on the use of normal human neuronal progenitor (NHNP) cells because of their importance in human nervous system regeneration, development and maintenance, but we have developed 2-D and 3-D bioreactors that can accommodate any cell line. In this Project, we will include the use of tissues important for physiological regeneration: Human osteoblasts or chondrocytes, and vascular cells. Our initial results with the NHNP cells were quite startling using extremely low-level electromagnetic fields (5 microtesla at 10Hz; 6mA). The low-amplitude, rapidly time-varying electromagnetic fields exert a very potent effect on the proliferation, morphology, and gene expression of the cells in culture, both in standard 2-dimensional culture plates as well as cells organized into 3-dimensional tissue-like assemblies (TLAs) in a 3D bioreactor. We have replicated our preliminary results many, many times, have analyzed the gene expression using gene arrays (followed by Luminex analysis for protein production), and have monitored cell proliferation, orientation, morphology, and glucose metabolism, and we are confident that we have a stable and reliable model to study the control of high-level cellular processes by application of low-amplitude, time varying electromagnetic fields (TVEMF) (1, 2). In additional studies at the University of Michigan, we have been able to generate functional in vitro engineered mammalian skeletal muscle, and have employed nerve-muscle co-culture techniques to promote axonal sprouting. We believe that nearly all tissues, in particular, neural, are susceptible to the influences of low-level TVEMF.

Goodwin, Thomas J.↗
NASA NTRS2007

Nutritional Status Assessment (SMO 016E)

It has not been possible to assess nutritional status of crew members on the ISS during flight because blood and urine could not be collected during ISS missions. Postflight observations of alterations in nutritional status for several nutrients are troubling, and we require the ability to monitor the status of these nutrients during flight to determine if there is a specific impetus or timeframe for these changes. In addition to the monitoring of crew nutritional status during flight, in-flight sample collection would allow better assessment of countermeasure effectiveness. SMO 016E is also designed to expand the current medical requirement for nutritional assessment (MR016L) to include additional normative markers for assessing crew health and countermeasure effectiveness. Additional markers of bone metabolism will be measured to better monitor bone health and the effectiveness of countermeasures to prevent bone resorption. New markers of oxidative damage will be measured to better assess the type of oxidative insults that occur during space flight. The array of nutritional assessment parameters will be expanded to include parameters that will allow us to better understand changes in folate and vitamin B6 status, and related cardiovascular risk factors during and after flight. Additionally, stress hormones and hormones that affect bone and muscle metabolism will also be measured. This additional assessment will allow us to better monitor the health of crew members and make more accurate recommendations for their rehabilitation. Several nutritional assessment parameters are altered at landing, but it is not known how long these changes persist. We extended the current protocol to include an additional postflight blood and urine sample collection 30 days after landing. Data are being collected before, during, and after flight. These data will provide a complete survey of how nutritional status and related systems are affected by space flight. Analyzing the data will help us to define nutritional requirements for long-duration missions. This expanded set of measurements will also aid in the identification of nutritional countermeasures to counteract, for example, the deleterious effects of microgravity on bone and muscle and the effects of space radiation.

Smith, S. M.↗

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